The present invention relates to a locking device. In various environments, especially for flight vehicles and projectiles, it is necessary to quickly and reliably release structural members for deployment yet securely hold such members in a retracted position for storage, transportation, or other pre-deployment requirements.
In certain applications such as smart bombs with movable fins (for guidance), missiles with movable fins, and satellite or space vehicles and equipment with deployable panels (e.g., solar panels), it is desirable to provide a large margin of safety in design. For such situations, the fins or panels are biased towards their deployment position with a large force, often a spring force. This force must be securely and reliably held in place prior to deployment. Premature deployment could easily damage the fins or panels, or cause other problems. Failure to deploy could result in an errant bomb or missile, or a satellite's premature loss of power.
In one proposed smart bomb design, a pin supported by plastic holds a first spring-biased member in place, which through mechanical linkage holds torsion springs in place. Mechanical linkage helps reduce the force to about 200 to 300 pounds needed to hold the spring-biased member in the locked position. When the pin is released, the torsion springs will cause the fins to be unlocked and thus deployed. To obtain a quick release, a predetermined amount of explosive is ignited to break the plastic, thereby, releasing the pin.
Another system to release a locking element or pin as used in airborne vehicles and projectiles includes cutting a bolt, which holds two elements relative to each other, so as to release satellite photovoltaic panels and antenna reflectors. A further system involves weakening a nut, e.g., by cutting a portion of the nut, then exploding the nut at the time of deployment. These systems all involve destruction, and are thus cumbersome and expensive to handle, test and replace.
In U.S. Pat. No. 6,224,013 to Chisolm, a tail fin deployment device uses lock balls to hold a cup member that in turn through linkage holds tail fins in a retracted position. A pin having recesses is spring-biased so that the recesses are in alignment with the apertures holding balls, but the pin is held by a lanyard in a position where its recesses are out of alignment with the balls. The lanyard is tied to the aircraft, so when the bomb is released, the lanyard comes out. Even in this design, the lanyard has to be pulled so as to overcome about 300 pounds of force from a spring. Moreover, this design necessitates hooking the lanyard to the aircraft.
Locking balls and the like have been used in various devices, such as manual positive lock pins, e.g., made by Pivot Point, Inc. of Hustisford, Wis. Pressing down on a button pushes a pin so as to align a recess in the pin with locking balls. When aligned, the balls enter the recess and release a locked member.
U.S. Pat. No. 6,074,140 to Cook secures a drill bit in place with a lock ball chuck. It is stated that a mechanical, solenoid or manual chuck may be used although no actual structure is shown.
U.S. Pat. No. 4,523,731 to Buitekant et al. uses a manual pull pin to release a plunger in turn releasing lock balls. The lock balls hold a flight vehicle to an external storage element. This manual release is disclosed as an alternative to the explosive severing of a bolt that held the flight vehicle and storage element together in a prior design.
U.S. Pat. No. 5,216,909 to Armoogam discloses an electromechanical locking mechanism for selective operation of a latch. A solenoid is used to push a pin down which pushes down a bolt locking pin, enabling movement of a piston transverse to the bolt locking pin.
Other patents using various locking mechanisms include U.S. Pat. No. 3,985,213 to Braggins, U.S. Pat. No. 5,628,216 to Qureshi et al., U.S. Pat. No. 4,289,039 to Trunner et al., U.S. Pat. No. 5,600,977 to Piron, and U.S. Pat. No. 4,565,183 to Smith.